fix(pypdfium): resolve overlapping text when merging bounding boxes (#1549)

get merged_text from boundingbox instead of merging it to prevent overlaps

Signed-off-by: Pedro Ribeiro <pedro_ribeiro_93@hotmail.com>

tests/data/groundtruth/docling_v1/2305.03393v1.json

@@ -2498,9 +2498,9 @@
         {
           "bbox": [
             148.45364379882812,
-            366.1537780761719,
+            366.1538391113281,
             464.3608093261719,
-            583.6257629394531
+            583.6257476806641
           ],
           "page": 2,
           "span": [
@@ -2541,9 +2541,9 @@
       "prov": [
         {
           "bbox": [
-            164.65028381347656,
+            164.6503143310547,
             511.6590576171875,
-            449.5505676269531,
+            449.550537109375,
             628.2029113769531
           ],
           "page": 7,
@@ -2563,7 +2563,7 @@
       "prov": [
         {
           "bbox": [
-            140.70968627929688,
+            140.70960998535156,
             198.32281494140625,
             472.73382568359375,
             283.9361572265625
@@ -2585,10 +2585,10 @@
       "prov": [
         {
           "bbox": [
-            162.67430114746094,
-            128.78643798828125,
-            451.70062255859375,
-            347.37744140625
+            162.67434692382812,
+            128.786376953125,
+            451.70068359375,
+            347.3774719238281
           ],
           "page": 10,
           "span": [
@@ -2607,9 +2607,9 @@
       "prov": [
         {
           "bbox": [
-            168.39285278320312,
+            168.3928985595703,
             157.99432373046875,
-            447.35137939453125,
+            447.3513488769531,
             610.0334930419922
           ],
           "page": 11,
@@ -4065,7 +4065,7 @@
             143.6376495361328,
             528.7375183105469,
             470.8485412597656,
-            635.6522979736328
+            635.6522827148438
           ],
           "page": 10,
           "span": [